Go here for more information on cancelling entire orders.
Follow these steps to cancel individual line items without cancelling the entire order:
Step 1: Select ORDERS and then ALL ORDERS.
Step 2: Use the filters and/or search function to locate a specific order. Then select the PO Number.
Step 3: On the order details page, scroll down to the Items area, which gives the status and details of individual line items. For the appropriate item(s), select the link Change Status.
Step 4: Using the Status drop-down menu, change the status of the item to Rejected. Then indicate the quantity of cancelled items. Best practice is to include a reason for the cancellation in the Reason for Change text box. The cancellation reason can help your retail partners avoid oversell issues in the future.
Please note the three available statuses: Accepted, Rejected, and Cancelled. In most cases, "rejected" and "cancelled" mean the same thing and can be used interchangeably. However, some retail partners may require a specific status to be selected. Please check with your trading partners to verify which status should be selected when canceling a line item.
Step 5: After saving, you can view the Items area again to confirm that the item you just edited has indeed been cancelled. You should see that the green check mark has changed to a red rejected symbol and that the cost has been crossed out.
Even after changing the status of a single line item to "Rejected," the other line items, as well as the status of the order itself, remain unaffected.